• Food Science of Animal Resources
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• v.28 no.2
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• pp.154-159
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• 2008

To investigate the rheological properties of protein mixed gels mediated by microbial transglutaminase (MTGase), pork myofibrillar protein (MFP), sodium caseinate (SC) and their mixture (MS), the various gels were incubated at different temperatures for various times. Extracted MFP, SC and their mixture (MS, 1:1) were incubated at different temperatures ($4^{\circ}C$ vs $37^{\circ}C$) for various times (0, 0.5, 2, 4 hr), and assessed for viscosity, gel strength and other characteristics using differential scanning calorimeter (DSC) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). DSC measurements showed that incubation at $37^{\circ}C$ rather than $4^{\circ}C$ caused marked changes in thermal transition, and MS displayed similar thermal curves (three endothermic transitions) to MFP and SC alone. After incubation at $37^{\circ}C$ for 2 hrs, the viscosity (cP) of MS increased (p<0.05) due to induction by MTGase, whereas no differences were observed at $4^{\circ}C$. However, gel strength values were no different, regardless of incubation temperatures and times. Future research will address how longer incubation times affect the functionality of protein mixed gels mediated by MTGase.

• Korean Journal of Microbiology
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• v.36 no.1
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• pp.26-32
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• 2000

Catechol 2,3-dioxygenase was purified from recombinant strain E. coli CNU312 carrying the tomB gene which was cloned from toluene-degrading Burkholderia cepacia G4. The purification of this enzyme was performed by acetone precipitation, Sephadex G-75 chromatography, electrophoresis and electro-elution. The molecular weight of native enzyme was about 140.4 kDa and its subunit was estimated to be 35 kDa by SDS-PAGE. It means that this enzyme consists of four identical subunits. This enzyme was specifically active to catechol, and$K_(m)$ value and $V_(max)$value of this enzyme were 372.6 $\mu$M and 39.27 U/mg. This enzyme was weakly active to 3-methylcatechol, 4-methylcatechol, and 4-chlorocatechol, but rarely active to 2,3-DHBP. The optimal pH and temperature of the enzyme were pH 8.0 and $40^{\circ}C$. The enzyme was inhibited by $Co^(2+)$, $Mn^(2+)$, $Zn^(2+)$, $Fe^(2+)$, $Fe^(3+)$, and $Cu^(2+)$ ions, and was inactivated by adding the reagents such as N-bromosuccinimide, and $\rho$-diazobenzene sulfonic acid. The activity of catechol 2,3-dioxygenase was not stabilized by 10% concentration of organic solvents such as acetone, ethanol, isopropyl alcohol, ethyl acetate, and acetic acid, and by reducing agents such as 2-mercaptoethanol, dithiothreitol, and ascorbic acid. The enzyme was inactivated by the oxidizing agent $H_(2)$$O_(2)$, and by chelators such as EDTA, and ο-phenanthroline.

• Applied Biological Chemistry
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• v.41 no.2
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• pp.125-129
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• 1998

Xanthomonas sp. isolated from soil exhibited cell wall lytic activity of Candida albicans and secreted chitinase in chitin media. Especially, the chitinase activity was induced by chitin and reached a maximum level at 3 days culture in chitin media. We constructed genomic library of Xanthomonas sp. using cosmid vector in E. coli. Oligonucleotide probe was synthesized from the consensus sequence corresponding to chitinase active site, which was derived from the comparison of amino acid sequences of bacterial chitinase genes. Using this oligonucleotide probe, we screened the genomic library. By restriction enzyme mapping of the positive clones, we identified 4 independent clones which may contain the chitinase gene. One of the clones, named pXCH1 (1.2 kb insert), was further analyzed. Northern blot analysis indicated that is transcripts, 1 kb and 0.8 kb, were induced by chitin. When the cloned gene was induced by IPTG in E.coli cell, chitinase activity which was secreted onto culture media was not observed. However, when the cell was disrupted by using sonicator and then centrifuged, the supernatant exhibited chitinase activity. SDS-PAGE of the supernatant indicated that about 35 kDa protein was induced by IPTG. From these results, it was concluded that the cloned DNA was one of the chitinase genes of Xanthomonas sp.

• Applied Biological Chemistry
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• v.35 no.1
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• pp.23-29
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• 1992

Bromelain was purified from Korean pineapple, Ananas comosus, L. The enzyme was purified about 21 fold by DEAF-cellulose ion-exchange chromatography and gel filtration on Sephadex G-150. Purified enzyme was confirmed as active single band by polyacrylamide electrophoresis and the molecular weight was estimated to be about 22,000 by SDS-PAGE. The optimum pH and temperature were 6.0 and $60^{\circ}C$, respectively. The range of its stability to the pH and temperature were respectively 5.0 to 7.0 and below $50^{\circ}C$. It was found that $Mn^{2+}$ increased the enzyme activity, whereas $Mg^{2+}\;and\;Fe^{2+}$ decreased it abruptly. The purified enzyme was inhibited by p-chloromercuribenzoic acid, indicating that reactive SH groups are required for the enzyme activity. The reaction of the enzyme followed typical Michaelis-Menten kinetics with Km value of $5.747{\times}10^{-4}\;M\;and\;Vmax\;of\;131.58\;{\mu}g/min$ for casein. When meat was treated with the enzyme, free soluble nitrogen and amino acid nitrogen increased as enzyme concentration increased.

• Proceedings of the Korea Society of Environmental Biology Conference
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• 2002.11a
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• pp.141-144
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• 2002

Environmental estrogens are natural or synthetic substances present in the aquatic environment, especially in effluent from sewage treatment. However, the adverse effects of these estrogenic substances on fish reproduction are unknown. Di-2-ethylhexyl phthalate (DEHP) is the most common phthalate, which Ps used as a plasticizer in polyvinylchloride (PVC), and it is widespread in the environment and has been found in aquatic organisms and sediments. Therefore, juvenile common carps (Cyprinus carpio) were exposed to nominal concentrations of 17$\beta$-estradiol (E2) (0.5, 5, 50 $\mu\textrm{g}$/L) and DEHP (10, 100, 500 $\mu\textrm{g}$/L) for 21 days, to determine the adverse reproductive effects of these compounds on plasma vitellogenin (VTG) induction, sex steroid level, and gonad weight. Electrophoresis (SDS-PAGE) revealed that much of VTG was induced in fish exposed to 5 and 50 E$_2$ $\mu\textrm{g}$/L, but none of DEHP exposure showed induction. Enzyme-linked immunosorbent assay (ELISA) revealed that VTG was significantly induced in fish exposed to 5 and 50 E$_2$ $\mu\textrm{g}$/L, and combination of 50 E$_2$ $\mu\textrm{g}$/L with 10 and 500 DEHP $\mu\textrm{g}$/L, but none of DEHP exposure showed induction. Analysis of sex steroid levels in some fish revealed that testosterone (T) was detected in both male and female fish of the control and DEHP exposures, but none of fish exposed to 22 concentrations had detectable testosterone level. On the other hand, E$_2$ exposure induced 17$\beta$-estradiol in plasma of male fish, but there was no induction of 17$\beta$-estradiol in plasma of male fish exposed to DEHP. Comparison of gonadosomatic index (GSI) revealed that maximal E$_2$ exposure inhibited ovarian growth, but maximal DEHP exposure stimulated testicular growth. The results indicated that those comparisons can be a useful bio-indicator for determining adverse reproductive effect of endocrine disrupting chemicals (EDCs).

• Journal of fish pathology
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• v.11 no.1
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• pp.43-50
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• 1998

In order to determine whether the tumor-inducing iridoviruses and the mortality-associated iridoviruses from cultured marine fish in Korea belong to same type, we compared the immunological characteristics of these viruses. The electrophoretical pattern of structural proteins of the tumor-inducing was different from that of the mortality-associated iridoviruses. The antigenicity of structural proteins of these viruses were identified by Western blotting using two monoclonal antibodies against tumor-inducing iridovirus. Two monoclonal antibodies recognized a 150 kDa structural protein of tumor-inducing iridoviruses showed. However, the structural proteins of the mortality-associated iridoviruses did not react with these monoclonal antibodies. These results demonstrate that the antigenicity of the structural proteins of tumor-inducing iridovirus is different from that of mortality-associated iridovirus, indicating that these two iridoviruses belong to different types.

• The Korean Journal of Food And Nutrition
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• v.9 no.4
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• pp.452-458
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• 1996

A PPIase gene of Bacillus stearothermophilus was screened from a genomic library by plaque hybridization using the A-1 primer as a probe. A PPIase positive plaque contained a 3.0kb insert of the chromosomal DNA. A 3.0kb fragment was subcloned into pUC18, resulting pPI1-40. A DNA fragment encoding the N-terminal portion of the PPIase in pPi-40 was amplified by polymerase chain reaction(PCR) method using the A-1 and B-2 primers. The amplified fragment was cloned into the Sma I site of pUC18 and recombinant plasmid was designated as pSN-18. The nucleotide sequence of 167bp fragment was determined. The deduced amino acid sequence of PPIase was completely matched with the determined N-terminal amino acid sequence of PPIase B. stearothermophilus. The translated protein sequence of PPIase B. stearothermophilus was compared with sequence from periplasmic PPIase from Escherichina coil ; homogies of 16 and 58%, respectively, were found. The clond PPIase gene was over-expressed in E. coil cell using pUC19 as an expression vector. The enzyme was partially purified by heat treatment and colum chromatochraphy on DEAE-Sepharose CL-6B. The molecular weight of the enzyme was dermined to be about 18.0 kDal by SDS-PAGE.

• Korean Journal of Food Science and Technology
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• v.43 no.6
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• pp.729-734
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• 2011

With the goal of transforming rice protein from an insoluble to a soluble form to increase the industrial utilization of rice wine meal (RWM), RWM was derivatized using commercial proteases and the RWM hydrolysates were characterized. Eight commercial proteases were used individually or in combination for hydrolysis of RWM. The degree of hydrolysis was assessed by determining the soluble protein in supernatant using the Lowry assay, protein in precipitates using a semimicro Kjeldahl procedure, and gravimetrically by the weight difference before and after hydrolysis. Protamex, Alcalase and Protease N proteases were most effective for hydrolysis of RWM. Although these assessment methodologies displayed some variation, they generally showed a similar pattern. When the aforementioned three proteases were simultaneously used to treat RWM, no significant difference was observed between the three assays (p<0.05) indicating an absence of enzymatic synergy.

• Journal of Food Hygiene and Safety
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• v.33 no.3
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• pp.193-199
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• 2018

In this study, PAT protein of genetically modified maize was prepared from the recombinant E. coli strain BL21 (DE3), and mice were immunized with the recombinant PAT protein. After cell fusion and cloning, two hybridoma cells (PATmAb-7 and PATmAb-12) were chosen since the monoclonal antibodies (Mabs) produced by them were confirmed to be specific to PAT protein in the indirect enzyme-linked immunsorbent assay (ELISA) and western blot tests. There were no cross-reactions of either Mabs to other GM proteins or to the extracts of non-GM maize. The ELISA based on the PATmAb-7 can sensitively detect 0.3 ng/g PAT protein in corn. These results indicate that the developed Mabs can be used as bio-receptors in the development of immunosensors and biosensors for the rapid and simple detection of GM corn adulterated in foods.

• Journal of Life Science
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• v.30 no.7
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• pp.592-597
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• 2020

Soybean [Glycine max (L.) Merr.] seeds contain an average of 40% protein on a dry weight basis, but they also contain antinutritional elements such as lectin, Kunitz trypsin inhibitor (KTI), and 7S α'- subunit protein. The objective of this research was to develop a new soybean genotype with triple recessive alleles for these elements. Three parents (Gaechuck#2, PI506876, and Le-16) were used to develop the genetic population, and the presence of lectin and KTI protein was detected using Western blot while 7S α' subunit protein was detected using SDS-PAGE. One F₃ plant strain with proper agronomical traits such as type, height, seed quality, and 100-seed weight was selected. The genotype of the developed strain is titilelecgy1cgy1, that is KTI, lectin, and 7S α' subunit protein free. The new strain has a purple flower, determinate growth habit, and light yellow pods at maturity. The seed has a buffer hilum and is yellow in color. The new strain's height was 58 cm compared to the Daewonkong cultivar at 46 cm, and its 100-seed weight was 27.1 g, smaller than the Daewonkong at 29.0 g. This is the first new soybean strain with the titilelecgy1cgy1 genotype, and it can be used to improve yellow soybean cultivars of high quality and function.